Use of composted refuse to make construction products

ABSTRACT

A process for converting municipal refuse into useable products such as building blocks, wall board, and building bricks which consists of the steps of reducing the size of the refuse to a chip size by shredding; decomposing the refuse in the presence of nitrogen, water and air; drying the chemically processed material in a gas fired dryer to render it biologically inert; grinding the dried material to a fine powder; mixing the powder with fillers and binders such as hydraulic setting cements and glues; adding water and other chemicals as required; forming the blocks or other building materials by pressing; and curing the product until a specified strength has been achieved.

c -zz-va AU 116 EX Aintablian 1 May 22, 1973 USE OF COMPOSTED REFUSE TO3,344,217 9/1967 Mogg et a1 l06/l22 MAKE CONSTRUCTION PRODUCTS 3,419,377/1968 3,579,320 /1971 1 Inventor: Avedis Ainublim, Santa Clara 3,653,8714/1972 Tempe ..71/14 Calif.

[73] Assignee: International Systems Management OTHER PUBLICATIONSCorporation Santa Clara Calif Business Week, July 12, 1969, page 145[22] Filed: Nov. 8, 1971 Primary Examiner-Lorenzo B. Hayes 1. N 196 7 7[211 App 0 6 Assistant ExaminerJohn H. Miller Related US. ApplicationData Att0rney-James R. Cypher [63] Continuation-impart of Ser. No.119,564, March 1,

1971, abandoned. [57] ABSTRACT A process for converting mun' [52]U.S.Cl. ..264/82,7l/9,7l/14, products such as building ,a -board, and106/1 1 106/1 106/137 building bricks which consists of the steps ofreducing [5 l -C --C C04) 5f 9/ 0 the size of the refuse to a chip sizeby shredding; [58] Field of Search ..264/32, 332, 109; decomposing therefuse in the presence of nitrogen,

water and air; drying the chemically processed material in a gas fireddryer to render it biologically inert; [56] Referenm C ted grinding thedried material to a fine powder; mixing the powder with fillers andbinders such as hydraulic UNITED STATES PATENTS setting cements andglues; adding water and other 516,112 3/1894 Ransome ..106/119 chemicalsas required; forming the blocks or other 1,777,449 l Rath 26 buildingmaterials by pressing; and curing the product 1 1 1927 Robens,

l 19 until a specified strength has been achieved. 1,941,817 H1934Sweeney et ...92/14 2,798,800 7/1957 Geraghty et a1.... ..71/ 14 13Claims, 2 Drawing Figures 3,243,327 3/1966 Hoppeler 264/37 3,236,6042/1966 Pierson ..71/9 3,236,605 2/1966 Pierson ..7l/9

GOMPOSTING RECElVlNG SORTING SHREDDIN'G s 7 n a 9 1o 11 12 4 DRYING 5smuome /Q 23 V 5124 19, w

COMPOUNDING COATING SHIPPING Patented May 22, 1973 2 Sheets-Sheet lOZEEIw QZEMOLSOO OZEQwmIm wzrrmow INVENTOR USE OF COMPOSTED REFUSE TOMAKE CONSTRUCTION PRODUCTS The present application is a continuation inpart of my prior co-pending US. Pat. application Ser. No. 119,564 filedMar. 1, 1971 and now abandoned.

BACKGROUND OF THE INVENTION Disposal of urban refuse is a critical,nationwide problem and extensive analysis and research are underway tofind viable solutions. The time-honored solution to refuse disposal,atmospheric burning, has ceased in all metropolitan areas. Open burninghas usually been replaced with earth burial using cut and-filltechniques. Nationally, this is a temporary solution since the largequantities of refuse produced in urban areas are rapidly consumingavailable sites. Incineration has been tried, but is is expensive andcontributes significantly to air pollution. Many costal cities dumprefuse at sea but this method must soon cease since there is evidencethat refuse contaminants are poisoning the local marine life.

There have been numerous attempts to economically produce buildingblocks from refuse. One process creates bricks out of the ashes ofincinerated refuse. Incineration, however, as previously stated, addsgreatly to the particle and thermal pollution of the air.

A Japanese process compacts refuse into blocks and coats them with tar.Thus far the Japanese blocks are unstable and cannot be used in buildingand have been found unsatisfactory in roads.

BRIEF SUMMARY OF THE INVENTION The gist of the present invention is aprocess for quickly converting municipal refuse into useful productswhich can be used to construct buildings. Accordingly, an object of thepresent invention is to provide a technically feasible and costeffective process for converting typical municipal refuse in urban areasinto a dense, hard stable, odor-free material which can be produced inmany forms such as cylinders, blocks having physical characteristicssimilar to commercial cement blocks and sheets for a variety of buildingpaving and decorating applications.

Another object is to stop the microbiology and chemical reactionsquickly so as to effect decomposition in a matter of days instead of theusual several months.

. A further object is to produce inert, sterile building constructionmaterials from refuse in an essentially continuous process, and whichwill retain its construc tion characteristics and integrity over a longperiod of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic drawing of theequipment used in the process of the present invention.

FIG. 2 is a flow diagram of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION ReceivingMunicipal refuse is delivered by trucks 1 or other means and dumped intoa receiver 2. The receiver holds the refuse from approximately twonormal size (36 cubic yard) collection trucks. The largest piece size isan object that will fit in a residential garbage can or an approximatemaximum of l A feet. Incoming refuse is approximately 74 cubic yardswith a density of approximately 270 pounds per cubic yard. Thus thereceiver holds about 10 tons of refuse which is about 40 percent byweight water. Refuse larger than 12 X 12 inches is screened mechanicallyby a screen graded belt 3 and the smaller classified refuse falls into areceiving hopper and is conveyed to a magnetic separator. The hopperfacilitates fly, rodent and odor control. The larger pieces of refuseare sorted for metal or other reuseable product recovery.

Magnetic Separator Refuse is conveyed to a magnetic drum or a magneticbelt where ferrous metals are extracted and conveyed to a metal bin forsalvaging. Iron separation may also be accomplished with a cross beltpickup.

Shredder The refuse remaining after the preceding separations is thenconveyed by belts 4 to a shredder which may be of conventional design.The shredder reduces all items to about 1 X 1 inch size chips. Thedensity of the refuse increases approximately 3.5 times and gives adischarge volume of slightly over cubic feet per hour.

Chemical Processing The waste is then delivered by conveyers 7 todeconditioning or composting tanks, 8,9, 10,11 and 12 for acceleratedbiological decomposition. Three days to a week is required fordecomposition. Consequently five or more tanks are needed.

Refuse delivered to the deconditioning tank is a mixture of wet materialchemically and bacteriologically active. Basically, de-conditioning is abiological process. The environmental factors influence the activitiesof the organisms in determining the speed and the course of thedecomposition cycle. The important factors are: particle size, moisturecontent, aeration, hydrogen ion concentration, temperature and initialcarbon-nitrogen ratio.

To accelerate the decomposition, the following steps are involved:

1. Turning the material at least once a day. The turning process willprovide aeration (oxygenation) 2. Maintaining a moisture content between40-70 percent. Water is sprayed periodically on the material to maintainthis moisture range.

3. Warm air is supplied periodically to maintain the temperature of thematerial between 50 C. to C.

4. Nitrogen is added periodically. The amount of nitrogen to be addeddepends upon the carbon content of the material. The ratio of carboncontent (C) to nitrogen content (N) to be added is C/N between 20 to 50percent by weight.

5. When the material has a pH of 6 or less, calcium carbonate or otherbase acid is added periodically to raise the pH slightly.

6. Composting reduces the particle size of most of the material andconsequently increases the density to approximately 40 pounds per cubicfoot. Moisture content of the material will be approximately 50 percent.

Drying After the chemical or deconditioning process, the material ismoved by conveyers 13 and 14 and dried by a gas fired heater 16 torender it biologically inert to facilitate grinding to a fine powder andto permit uniform compounding of the final product. Between 60 topercent moisture of the composted material is removed in several hoursby the gas fired dryer at a temperature of between to 210 F. The driedmaterial is then conveyed by conveyer 17 to the grinder 18.

Grinder The dry material is ground to a fine powder form. To achieve themesh size needed (approximately 80 mesh size) two passes of the grindingprocess are required. The ground-up material is then conveyed byconveyer 19 to a mixing tank 21.

Mixing Tank In the mixing tank 21, the fine powdered form material ismixed with additives and binders to provide the required physicalcharacteristics. Dry materials are fed from overhead storage tanks 22and 23 by proportioning feeders 24 and 25 to the mixer. The basicingredients of the mixture are as follows:

Mixture Ratio of Mixture (per cent by weight) 1. De-conditioned material100% 2. Plaster of Paris to 50% 3. Lime 0% to 50% 4. Silica, as in theform of sand 0% to 60% 5. Calcium as in the form of gypsum (selenite,alabaster, satin or spar) 0% to 50% 6. Portland Cement 0% to 30% 7.Water 25% to 110% The meaning for Portland Cement in the specificationand claims is a kind of cement that hardens under water, and isbasically made by burning a mixture of limestone and clay, shale, blastfurnace slag, marl, iron ore and gypsum. Portland cement is readilyattainable as the type ordinarily used in making concrete in buildingconstruction. Portland Cement for construction is identified by ASTM NO.C-150. Quick setting cements may also be used such as by (1) heatingbauxite and lirnestone and then grinding to a fine powder, (2)tricalcium silicate or (3) oxychloride cements (BMgOMgCI lOl'LO).

Three main categories of mixtures are listed below: Example 1 MixtureRatio of Mixture (per cent by weight) 1. De-conditioned material 100% 2.Plaster of Paris 20% to 60% 3. Silica (sand) 25% to 80% 4. Water 26% to110% Example 2 l. Deconditioned material 100% 2. Plaster of Paris 20% to60% 3. Portland cement to 30% 4. Water 25% to l 10% Example 3 1.De-conditioned material 100% 2. Plaster of Paris 25% to 50% 3. Portlandcement 10% to 30% 4. Lime 25% to 60% 5. Silica (sand) 30% to 80% 6.Water 25% to 110% The correct amount of liquid is controlled by thefeeder. Operation of the mixer is continuous and retention time withinthe mixing chamber is variable.

Molding The mixture which is prepared in the mixing tank is conveyed toa press 27 for molding into block form 20. The molding pressure willvary between a load of 15,000 pounds to 75,000 pounds. The pressure isheld for about 1 minute or longer to insure that the blocks will bestabilized. Higher pressures are required for larger blocks.

Curing The blocks are stacked in a curing room 29 with high moisturecontent. Water spray, as overhead fixtures, provides suspended waterspray continuously. The blocks are cured between 1 day to 10 days. Theblocks are then ready for use and are stacked in the open air in a yard.

Coating As required, the blocks may be coated with plastic as by dippingin a tank 30 to give them the desired architectural characteristics.Further examples and testing results Sample No. 1 Series Sample 1ADeconditioned material 300 grams Plaster of Paris 150 grams PortlandCement grams Water 400 grams Sample 18 same as 1A except water 350 gramsSample 1C same as [A except water 300 grams Sample ID same as 1A exceptwater 250 grams Test results of Sample No. 1 Series Block sixe for thesamples in series 1 was 1 X1 X4 inches.

Sample No. 2 Series 1n a second series of test samples, the sameformulation as the sample No. 1 series was used except that 400 grams ofwater was added and the curing time was increased. The test resultsshowed a dramatic increase in compressive strength as indicated by testsby Twining Laboratories of Southern California, Inc. as follows: Testresults of Sample No. 2 Series (1 1% diameter cylinders) Specimen LoadCompressive Strength No. 1 3,720 lbs. 2,105 psi. No. 2 3,260 lbs. 1,845psi. No. 3 3,420 lbs. 1,935 psi. No. 4 3.120 lbs. 1,766 psi.

Sample No. 3 Series De-conditioned material 45% Silica (sand) 75%Plaster of Paris 1 1.2% Portland Cement 6.8% Water 25 to 30% Testresults of Sample No. 3 series The average compressive failure was 1,400psi. Sample No. 4 Series Specimen Decondi- Plaster Portland 11,0 Moldingtioned Mixture of Paris Cement gr. Pressure grams grams grams lbs. A 10040 20 122 15,000 13 100 40 20 100 20,000 C 100 40 2O 60 30.000 D 100 4020 25,000 E 40 20 40 35,000 F 100 40 20 122 15,000 6 Deconditionedmaterial 100 grams Silica (sand) 100 grams Lime 10 grams Water gramsBacteriological Tests Tests for bacteriological activity and for pHreading were conducted by the Orange Coast College in Costa Mesa,California and the results are shown below:

neg neg neg neg neg pH Tests All pl-l tests were performed by dissolving1 gram of material in milliliters of pH 7.0 buffer. Results are based onthe average of three readings.

The foregoing test show that blocks having compressive strength of 1,450psi are obtainable which is in excess of the compressive strength ofcommercial cement blocks which is between 800 and 1,240 psi. Further thebacteriological tests show that the block is inert and may in fact bemore inert than commercial cement block because it is essentiallynon-porous and therefore bacteria has a difficult time growing in thepresent block.

In the deconditioning step of the process it has been found thatnitrogen may be introduced in the form of ammonium sulfate, (NI-M 50nitrogen tri-oxide, N 0 ammonium nitrate, NH NO sodium nitrate, NaNO orequivalent.

Referring to FIG. 2, a flow diagram is shown for the operation of aplant having a capacity of 100 tons of refuse per day. This refuse has avolume of 740 cubic yards and a water content of 40 percent. The densityand water content will of course vary but a typical density is about 270pounds per cubic yard. Such a plant should have a receiver having acapacity to take 12.5 tons of refuse per hour with a volume of 2,500cubic feet per hour. Density is about 10 pounds per cubic foot with awater content still at 40 percent and still containing the large pieces.

The product is fed through a standard shredder which has a capacity of12.5 tons per hour and processes 715 cubic feet per hour. The density israised by shredding to 35 pounds per cubic foot. The size is reduced toabout 1 inch and the water content remains at 40 percent.

In the de-conditioner, nitrogen in the form of ammonium nitrate or theother compounds of nitrate set forth above are added in the amountsabove specified. The de-conditioner should have a capacity of about 690cubic feet per hour with a weight capacity of 13.8 tons per hour.Density again increases to 40 pounds per cubic foot and the watercontent is raised by the addition of water to 50 percent. Size is nowreduced to ls-l inch.

in the dryer which has a capacity of 7.5 tons per hour and a volume of470 pounds per cubic foot the density is increased to 32 pounds percubic foot and the water content is negligible. Size is further reducedto oneeight inch to 1 inch.

After grinding, the following materials in batch quantities are added.Water, 1.1 tons per hour, 35.3 cubic feet per hour with a density of62.4 pounds per cubic foot. Lime, 1.1 tons per hour at a volume of 33.9cubic feet per hour and a density of 65 pounds per cubic foot. Size isASTM 100. Silica is added at the rate of 7.5 tons per hour at a volumeof 188 cubic feet per hour and having a density of 80 pounds per cubicfoot and a size of ASTM 100.

For extra strength Portland cement may be added at the rate of 1.8 tonsper hour having a volume of 45 cubic feet per hour at 94 pounds percubic foot.

The de-conditioned product added to the mixer at this point in theprocess is 7.5 tons per hour with a volume of 300 cubic feet per hour.Density is 50 pounds per cubic foot and water content is 3 per cent.Size is 0.006 to 0.01 inches (ASTM 100 50).

The above process makes about 32,500 blocks per day in a molder whichsubjects each block to 31,200 psi. at a rate of 1,980 blocks per hourworking 17 hours per day.

Wall board is made by taking dry de-conditioned material in a ratio ofabout to 90 percent from the dryer and mixing it with 10 to 25 percentElmers Glue or equivalent (such as Resorcinol water proof glue by U.S.Plywood or any marine glue used by companies to make plywood) andpressing between two sheets for forming. The wall board is then driedfor about 24 hours. Other glues which may be used are Plyobord SuperGlue by Goodyear and two component epoxy glues.

Floor tile is best made using 75 to 90 percent deconditioned materialand 10 to 25 percent Plyobord Super Glue or Elmer's Glue.

It is to be understood that the process described above and the sizesgiven are exemplary only. By changing the size and proportions of theformulas a plant can handle anywhere from 100 tons a day to a 1,000 tonsa day or more.

1 claim:

1. A process for converting municipal refuse that is chemically andbacteriologically active to building construction blocks comprising:

a. shredding said refuse and reducing it to approximately 1 inch chipsize;

b. de-conclitioning said shredded refuse for approximately 3 to 7 daysin a de-conditioning tank including the steps of:

1. adding nitrogen in a form selected from the group consisting ofammonium sulfate, nitrogen tri-oxide, ammonium nitrate and sodiumnitrate, periodically so that the ratio of carbon content to nitrogencontent is between 20 and 50 by weight,

2. adding water so that the moisture content is between 40 and 70percent,

3. maintaining a temperature between 50 and 4. aerating thedeconditioned material as by turning periodically,

5. maintaining a pH of slightly more than 6,

c. drying said de-conditioned material and removing 60 to percent of thewater;

d. grinding said dried de-conditioned material to a fine powder form:

e. adding additives and binders selected from the group consisting ofplaster of paris, lime, silica, portland cement, calcium in a formselected from the group consisting of gypsum, selenite, alabaster,satin, and spar, and water and mixing;

f. compressing the mixture into a pre-selected mold;

and

g. curing the molded product in a moist atmosphere until the desiredstrength has been achieved.

2. A process as defined in claim 1 comprising:

a. said nitrogen being added in the form of ammonium sulfate.

3. A process as defined in claim 1 comprising:

a. said nitrogen being added in the form of nitrogen tri-oxide.

4. A process as defined in claim 1 comprising:

a. said nitrogen being added in the form of ammonium nitrate.

5. A process as defined in claim 1 comprising:

a. said nitrogen being added in the form of sodium nitrate.

6. A process as defined in claim 1 comprising:

a. said pH being maintained by the addition of calcium carbonate.

7. A process as defined in claim 1 comprising:

a. said binders and additives consisting of plaster of paris and silica.

8. A process as defined in claim 1 comprising:

a. said binders and additives consisting of plaster of paris andportland cement.

9. A process as defined in claim 1 comprising:

a. said binders and additives consisting of plaster of paris, portlandcement, lime and silica.

10. A process as defined in claim 1 comprising:

a. said binders and additives consisting of plaster of paris, lime,silica, calcium (in a form selected from the group consisting of gypsum,selenite, alabaster, satin, or spar), and portland cement.

11. A process as defined in claim 1 comprising:

a. said compression step being held for at least about I minute.

12. A process for converting municipal refuse that is chemically andbacteriologically active to building wall board comprising the steps of:

a. shredding said refuse and reducing it to approximately 1 inch chipsize;

b. de-conditioning said shredded refuse for approximately three to sevendays in a deconditioning tank including the steps of:

1. adding nitrogen periodically so that the ratio of carbon content tonitrogen content is between 20 and 50 by weight,

2. adding water so that the moisture content is between 40 and percent,

3. maintaining a temperature between 50 and 4. aerating thede-conditioned material as by tuming periodically 5. maintaining a pH ofslightly more than 6 c. drying said de-conditioned material and removing60 to percent of the water;

d. adding a glue binder and mixing; and

e. compressing the mixture of de-conditioned material and glue additiveinto a sheet; and

f. curing said sheet until the desired strength has been achieved.

13. A process for converting municipal refuse that is chemically andbacteriologically active to building floor tile comprising the steps of:

a. shredding said refuse and reducing it to approximately 1 inch chipsize;

b. deconditioning said shreeded refuse for approximately three to 7 daysin a deconditioning tank including the steps of:

1. adding nitrogen periodically so that the ratio of carbon content tonitrogen content is between 20 and 50 percent by weight,

2. adding water so that the moisture content is between 40 and 70percent,

3. maintaining a temperature between 50 and 80 4. aerating thedeconditioned material as by turning periodically,

5. maintaining a pH of slightly more than 6,

c. drying said deconditioned material and removing 60 to 90 percent ofthe water;

d. adding 10 to 25 percent by weight of a glue binder and mixing; and

e. compressing the mixture of deconditioned material and glue additiveinto a sheet; and

f. curing said sheet until the desired strength has been achieved.

* t t i

2. A process as defined in claim 1 comprising: a. said nitrogen beingadded in the form of ammonium sulfate.
 2. adding water so that themoisture content is between 40 and 70 percent,
 2. adding water so thatthe moisture content is between 40 and 70 percent,
 2. adding water sothat the moisture content is between 40 and 70 percent,
 3. maintaining atemperature between 50* and 80* C.,
 3. maintaining a temperature between50* and 80* C.,
 3. maintaining a temperature between 50* and 80* C., 3.A process as defined in claim 1 comprising: a. said nitrogen being addedin the form of nitrogen tri-oxide.
 4. A process as defined in claim 1comprising: a. said nitrogen being added in the form of ammoniumnitrate.
 4. aerating the deconditioned material as by turningperiodically,
 4. aerating the deconditioned material as by turningperiodically,
 4. aerating the de-conditioned material as by turningperiodically
 5. maintaining a pH of slightly more than 6 c. drying saidde-conditioned material and removing 60 to 90 percent of the water; d.adding a glue binder and mixing; and e. compressing the mixture ofde-conditioned material and glue additive into a sheet; and f. curingsaid sheet until the desired strength has been achieved.
 5. maintaininga pH of slightly more than 6, c. drying said de-conditioned material andremoving 60 to 90 percent of the water; d. grinding said driedde-conditioned material to a fine powder form: e. adding additives andbinders selected from the group consisting of plaster of paris, lime,silica, portland cement, calcium in a form selected from the groupconsisting of gypsum, selenite, alabaster, satin, and spar, and waterand mixing; f. compressing the mixture into a pre-selected mold; and g.curing the molded product in a moist atmosphere until the desiredstrength has been achieved.
 5. maintaining a pH of slightly more than 6,c. drying said deconditioned material and removing 60 to 90 percent ofthe water; d. adding 10 to 25 percent by weight of a glue binder andmixing; and e. compressing the mixture of deconditioned material andglue additive into a sheet; and f. curing said sheet until the desiredstrength has been achieved.
 5. A process as defined in claim 1comprising: a. said nitrogen being added in the form of sodium nitrate.6. A process as defined in claim 1 comprising: a. said pH beingmaintained by the addition of calcium carbonate.
 7. A process as definedin claim 1 comprising: a. said binders and additives consisting ofplaster of paris and silica.
 8. A process as defined in claim 1comprising: a. said binders and additives consisting of plaster of parisand portland cement.
 9. A process as defined in claim 1 comprising: a.said binders and additives consisting of plaster of paris, portlandcemenT, lime and silica.
 10. A process as defined in claim 1 comprising:a. said binders and additives consisting of plaster of paris, lime,silica, calcium (in a form selected from the group consisting of gypsum,selenite, alabaster, satin, or spar), and portland cement.
 11. A processas defined in claim 1 comprising: a. said compression step being heldfor at least about 1 minute.
 12. A process for converting municipalrefuse that is chemically and bacteriologically active to building wallboard comprising the steps of: a. shredding said refuse and reducing itto approximately 1 inch chip size; b. de-conditioning said shreddedrefuse for approximately three to seven days in a deconditioning tankincluding the steps of:
 13. A process for converting municipal refusethat is chemically and bacteriologically active to building floor tilecomprising the steps of: a. shredding said refuse and reducing it toapproximately 1 inch chip size; b. deconditioning said shreeded refusefor approximately three to 7 days in a deconditioning tank including thesteps of: